This application is based on Patent Application Nos. 2000-256202 filed Aug. 25, 2000 in Japan and 2001-047750 filed Feb. 23, 2001 the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a system for recycling resinous materials from resin mold products recovered from discarded apparatuses (such as home electric appliances, electronic devices or cars), more particularly to a crushing system for crushing polymer parts obtained by disassembling the recovered products to reduce the volume thereof; a classifying system for classifying the resinous materials into their kinds, preferably into kinds of fire retardants added thereto; and a cleaning system for removing foreign matters such as coated films, labels or seals applied to the products or other contamination thereof.
2. Description of the Related Art
Plastics light in weight and excellent in mechanical strength have often been used for home electric appliances, OA apparatuses, communication apparatuses or others as internal parts or external casings thereof. From a point of view of the environmental protection, the conversion from a mass-production/mass-scrap economy in the past to a circulation type economy is required. In such a recent trend, a full-scale recycle of resinous products has been urgently demanded; for example, the recycling of home electric appliances has been obligated by law. However, regarding the material recycle in which the resin mold products are recovered and reused as resinous materials, it is done solely in a case wherein it is possible to specify to some extent what kind of resin is used, because there is a problem peculiar to the resin in that if different kinds of resins are mixed together, functions inherent to the resin are significantly damaged. Accordingly, a resin recycling system is desired, which is capable of correctly classifying various kinds of resinous products used in the discarded appliances or apparatuses and regenerating the same as fresh resinous materials for the home electric appliances, OA apparatuses or communication apparatuses.
To proceed a high-quality recycling, it is necessary to correctly identify and classify materials of resin mold products containing various kinds of additives including fire retardant. Regarding the identification of materials of the resin mold products, a high-performance resin identification device has recently been developed, and is becoming reality. This device, however, necessitates a considerable care on the operation, maintenance and inspection thereof as well as it is expensive in cost. The most effective method for identifying materials of the resin mold products solely from a point of view of the material identification is to provide such a resin identification device in each of the disassembly factories. This method is, however, problematic from the economical view point or a view point of stable operation of the system.
To operate the above-mentioned resin identification device under the stably controlled condition, it is desirable to provide the disassembly factory for recovering the resin mold products at a position different from that of the resin identification device. In such a case, it is necessary to convey the resin mold products from the disassembly factory to the position at which the resin identification device is provided.
However, the resin mold products obtained from the discarded apparatuses have various shapes and sizes distributed from a small one to an extremely large one. Therefore, if they are packed into a box or a bag while maintaining their shapes, the physical transportation cost becomes wasteful since a bulk specific weight is very small to reduce a weight relative to a volume thereof. Accordingly, it is desired to crush the resin mold products into pieces having an economically preferable size (a size capable of achieving a proper transportation efficiency). As a crusher used for this purpose, it is possible to use a commercially available crusher such as a hammer mill, a cutter mill, a two-axis crusher and the like which is capable of crushing the resin mold products into pieces having about 50 mm or less in size.
However, the resin mold products recovered from disassembling appliances have various sizes as set forth above. In order to load all of the resin mold products and crush them into pieces having about 50 mm or less in size, it becomes necessary to provide a very big crusher having a loading opening. Since these equipment is costly, there is a problem that it is economically impossible to install such expensive equipment at each of small factories.
Further, if the resin mold products are crushed altogether by such means, however, many of the resin mold products formed of different kinds of resins are crushed in a mixed state, and, as a result, it is necessary to identify crushed pieces in which many kinds of resins exist using an identification apparatus. Although such identification is possible in principle, industrialization thereof is difficult in practice because it is necessary to respectively identify kinds of resins of a large number of crushed pieces and classify the same into the respective materials after the identification.
In addition, to economically realize the material recycling of high-quality resinous materials, it is necessary to classify kinds of resins containing various additives such as fire retardant at a high accuracy and a high speed. As a method for classifying the kinds of resins, a technique using, for example, a near infrared ray absorption has been known and various devices are marketed. However, this method hardly identifies kinds of resins with many identification errors and is unsuitable for the high accuracy and high speed identification. Another method utilizing intermediate infrared absorption has been also known. Although this method is capable of identifying not only kinds of resins but also those of additives such as fire-retardant at a high accuracy, there is a problem in that a long time is required for the identification and therefore unsuitable for a high speed processing.
On the other hand, the recovered resinous products may be coated with films, applied with labels or the like or carry various contaminants, which are liable to enter the resin during the treatment of the resinous products to result in a problem to significantly deteriorate the characteristic of the resin to be reused.
Although various trials have been attempted for removing foreign matters carried on the surface of the resinous product, for example, by a mechanical method and the separation or removal with a solvent, there is a problem in either cases. For instance, if the removal of the coated film or the label is intended by using a crusher such as a ball mill, the resin is softened due to heat generated by the friction during the crushing operation, which disturbs the resin removal or causes the re-adhesion of the foreign matters once removed. Also, there is another method wherein the foreign matters are dissolved with a solvent and then separated and removed from the resin. This method, however, has a serious problems in that the used solvent must be regenerated or discarded, and also has other problems in that an apparatus used therefor is complicated in structure and unfavorable from the economical point of view.
There is a still further method for removing the coated film or labels, called as a dry blast treatment, wherein an abrasive material such as sands or metallic particles is used for scraping off the foreign matters from the surface of the resinous product. According to this method, however, particles of the abrasive material may stick into the surface of the resinous product and remain as they are as new foreign matters. Also, the resin may be softened by heat generated due to the friction of the abrasive material and cause the re-adhesion of the foreign matters once removed.
The present invention has been done to solve the above-mentioned problems, and an object of the present invention is to provide a resin recycling system for crushing resin mold products collected from discarded apparatuses into crushed resinous pieces to reduce an apparent volume thereof, without identifying that the resin mold product belongs to what kind of resin but with taking care that a plurality of kinds of resins are not mixed with each other; identifying a kind of the crushed resinous pieces to classify the same to that kind for easily determining a field in which the same is reused; and removing foreign matters from the surface of the classified crushed resinous piece to be reusable as resinous material.
Another object of the present invention is to provide a crushing system for roughly crushing polymer parts (including a large-sized ones) taken out from the collected and disassembled apparatuses to reduce an apparent volume thereof.
A further object of the present invention is to provide an identification system for effectively identifying a kind of crushed resinous pieces obtained by crushing resin mold products collected from discarded electric or electronic equipment without identifying that the resin mold product belongs to what kind of resin but with taking care that a plurality of kinds of resins are not mixed with each other.
Further, the present invention is to solve the above-mentioned problems of the prior art by providing a cleaning system for thermoplastic resin products wherein, when the resin products are collected and cleaned to be reusable resinous material, foreign matters such as coated films or labels adhered on the surface of the resin products are sufficiently removed therefrom so that the resinous material is usable in the same field as before.
To achieve the above objects, according to one aspect of the present invention, a resin recycling system is provided, which comprises crushing means for individually crushing resin mold products into crushed resinous pieces in which 70% or more of the crushed resinous pieces have an equivalent diameter in a range from 1 to 50 mm, packing means for packing the crushed resinous pieces of the respective mold product into a bag having a transparent portion, classification means for irradiating a light beam to the crushed resinous pieces in the bag through the transparent portion, identifying a kind of the crushed resinous pieces based on a reflected beam therefrom, and classifying the bags into respective kinds of resins, and cleaning means for taking the crushed resinous pieces out from the bag and cleaning the crushed resinous pieces of the respective kind to remove foreign matters adhered on the surface thereof.
In the above description, the term, xe2x80x9cequivalent diameterxe2x80x9d is a diameter of a circle having the same area as that of a projected area of an object.
Here, the equivalent diameter of the crushed resinous piece is preferably in a range from 3 to 40 mm, more preferably from 5 to 30 mm. A ratio of the crushed resinous pieces having the equivalent diameter within these ranges is preferably 80% or more, more preferably 90% or more.
If the equivalent diameter of the crushed resinous piece is smaller than 1 mm, there is an inconvenience in that foreign matters could not be removed during cleaning by the cleaning means, because the crushed resinous piece is pulverized. For example, when the cleaning is carried out by the abrasion, the abrasion becomes impossible. Also, the small resinous pieces are liable to stick to the interior of the crusher or the bag due to static electricity.
On the other hand, if the equivalent diameter of the crushed resinous piece exceeds 50 mm, the crushed resinous pieces may be still three-dimensional to obstruct the sufficient volume reduction.
The crushing may be carried out at one step. However, if the mold product is too large in size to be introduced into an ordinary crusher, the crushing may be carried out at two steps wherein the mold product is roughly crushed by a rough crusher and then introduced into the ordinary crusher.
Since one resin mold product is formed of one kind of resin, it is possible to effectively reduce the apparent volume of the resin mold product while preventing the finely crushed resinous pieces from mixing with other kinds by crushing the resin mold product separately one kind by one kind and immediately packing into a bag. By crushing the resin mold product one by one which is recovered from the discarded apparatus in the manual disassembly factory and packing the crushed resinous pieces in a bag, the conveying efficiency is enhanced.
Since the crushed resinous pieces in the bag is of the same kind of resin, it is possible to carry out the economical classification by classifying the bags.
In this regard, to further enhance the working efficiency, when it is apparent in advance that the mold products are formed of the same kind of resin, they are crushed together and packed in one bag. For example, if there are plurality of mold members of the same shape and function (such as paper feeding trays of different sizes of a copying machine) and it is confirmed that they are formed of the same kind of resin, they may be crushed together and packed in one bag. This method is favorable for facilitating the working efficiency when there are a number of small resinous members of a similar shape and the same kind of resin in one discarded apparatus.
The transparent portion of the bag is necessary for the purpose of preventing the light beam irradiated to the crushed resinous particles or reflected therefrom from being adversely effected by the passage thereof through the bag. Accordingly, if the adverse effect on the detection due to the passage of light beam through the bag is negligible, the transparent portion is not necessarily completely transparent. In short, it is sufficient that the bag is provided with a light-passing area (transparent portion) which does not adversely effect the detection, and in this text, such a light-passing area is referred to as a transparent portion. The transparent portion may extend throughout the bag. Such a bag may be formed, for example, of polyethylene. In this regard, a thickness of the transparent portion is generally 100 xcexcm or less. Other materials may be used for this purpose, such as resinous film, resinous net or metallic net.
A method for identifying a kind of resin includes, for example, one based on a Raman spectrum analysis, wherein a Raman spectrum obtained from the reflected light beam from the resin to be inspected (i.e., the crushed resinous pieces in the bag) is sequentially compared with Raman spectra obtained from reflected light beams from various known resins prepared in advance to find whether or not there is the coincidence between both the spectra. The method based on the Raman spectrum analysis is favorable because it is less adversely effected from color tone or surface contamination of the crushed resinous piece. One method for identifying kind of resin based on the Raman spectrum analysis is disclosed, for example, in paragraphs from 0011 to 0018 of Japanese Patent Application Laid-open No. 10-38807. Alternatively, an infrared or near infrared spectrum analysis may be used for this purpose.
One method for classifying the bags into kinds of resins includes the steps of storing an identified kind of crushed resinous pieces and an expected arrival time at which the bag of the crushed resinous pieces would reach a predetermined classification position on a conveying path, in correspondence to each other, and recovering the bag reaching the classification position at the expected arrival time from the conveying path.
The predetermined classification position may be different in accordance with kinds of resins. In such a case, the classified recovery is carried out wherein, for example, the bag in which resin A is packed is recovered from the conveying path at the classification position for the resin A, and the bag in which resin B is packed is recovered from the conveying path at the classification position for the resin B.
The predetermined position may be a specified one irrespective of kinds of resins. In such a case, the classified recovery is carried out in such a manner that the bag of resin A (the resin A is packed) reaching the classification position is guided from the conveying path to a collecting container or the like for the resin A, and similarly, the bag of resin B reaching the classification position is guided from the conveying path to a collecting container or the like for the resin B.
The expected arrival time is obtained by an identification time, a distance between an identification position and the classification position, and a conveying speed. While the expected arrival time may be calculated from these data every time, it may be determined as a time a predetermined period after an identification time, since the above distance and the conveying speed are constant.
The cleaning means removes foreign matters such as plated layers, coatings, labels or contaminants adhered to the surface of the crushed resinous piece therefrom.
The cleaning means may be a device having a cleaning vessel and an agitator member provided in the cleaning vessel wherein at least part of the inner wall of the cleaning vessel and/or a surface of the agitator member has an abrasive surface (roughened surface) for removing (scraping or scrubbing off) the foreign matters on the surface of the crushed resinous piece. Water or an aqueous rinsing liquid may be supplied into the vessel to enhance the removal of foreign matters.
The abrasive surface (roughened surface) may be of any structure, provided it could sufficiently clean the surface of the crushed resinous piece. The abrasive surface preferably has the irregularity having a depth in a range from 40 to 2000 xcexcm. By the contact of crushed resinous pieces with this roughened surface having such irregularity, foreign matters such as coated film or label adhered onto the surface of the crushed resinous piece are sufficiently scrubbed or scraped off and removed. If the depth of the irregularity is less than 40 xcexcm, the foreign matters are not sufficiently removable. Contrarily, if exceeding 2000 xcexcm, the surface of the crushed resinous piece is excessively scraped off to lower the resin recovery percentage. The depth of the irregularity is preferably in a range from 50 to 1000 xcexcm, more preferably from 60 to 500 xcexcm. If the depth is within such a range, the foreign matters are not excessively scraped off but sufficiently removable.
In the device for continuously cleaning the crushed resinous pieces, the crushed resinous pieces are continuously supplied from one end of the cleaning vessel, conveyed in one direction within the cleaning vessel, for example, by a screw or others and continuously collected from the other end. If water or aqueous liquid is used in such a device, the feeding of water or aqueous liquid is carried out in a similar manner that the water or the aqueous liquid is also continuously fed from the one end and/or intermediate portions of the cleaning vessel, flows in the same direction in the cleaning vessel and is continuously drained from the other end.
When water or aqueous liquid is used during the cleaning operation, it functions as a lubricant between the crushed resinous pieces and the irregularity to prevent the surface of the crushed resinous piece from being excessively scraped off as well as to suppress the temperature rise of the crushed resinous piece due to the cooling operation of water whereby the softening thereof is inhibited. Also, the foreign matters such as coated film or label once removed are quickly discharged out of the cleaning device and do not adhere again to the crushed resinous pieces.
The resin recycling system may have a recovery means for separating foreign matters from a mixture of the crushed resinous pieces cleaned by the cleaning means and the foreign matters and recover the crushed resinous pieces. The crushed resinous pieces and the foreign matters may be separated from each other, for example, by wind. Also, magnet force may be used for removing metallic material. When water or aqueous liquid is used for the cleaning operation, it is possible to remove foreign matters together with water or the like. In this regard, it may be so adapted that, after removing foreign matters from water or aqueous liquid through a filter or others, the water or aqueous liquid is reused.
The resin mold products which can be recycled after being crushed, classified and cleaned according to the present invention include, for example, those used as housings or parts of various apparatuses used in an OA and home electric appliance field, an electric and electronic field, a sanitary field, an automobile field or a sundries field. For example, various resinous housings, trays or internal resinous parts used in copying machines, printers, personal computers, TV sets, various monitors or mobile telephones.
The resinous material recycled according to the present invention includes, for example, various styrene type resins such as acrylonitrile-butadiene-styrene resin, polystyrene resin or acrylonitrile-styrene resin; polycarbonate resin; olefin type resin such as polyethylene or polypropylene; polyamide type resin such as PA 6, PA66, PA46 or PA12; polyester type resin such as polybutylene terephthalate, polyethylene terephthalate or polyacrylate; polyphenylene ether resin; polyacetal; polyvinylchcloride resin; polysulfon; PPS; polyether sulfon; ethylene-vinylacetate copolymer; ethylene-ethylacrylate copolymer; EVOH; polyamide type elastomer; polyester type elastomer; and alloys in which two or more of them are mixed. These are all identifiable by the classification means of the inventive system.
The classification means of the inventive system can identify additives contained in the crushed resinous pieces, such as various fire-retardants including halogen type and phosphor type; various fire-retardant assistants such as antimony trioxide, antimony tetroxide, antimony pentoxide, chlorinated polyethylene or tetrafluoroethylene polymer; inorganic filler such as glass fiber, carbon fiber, metallic fiber or talc; anti-fungus agent, mildewcide, plasticizer, antistatic or silicone oil. These additives are identifiable if a considerable amount of them is contained in the crushed resinous piece (resin mold product), for example, 1 part by weight or more, preferably 2 parts or more in 100 parts by weight of the resin mold product.
To achieve the above objects, one aspect of the crushing system according to the present invention comprises an endless conveyor for conveying polymer mold products, and an opposed member having an opposed surface confronting at least one end of the endless conveyor on the conveying-directional side and disposed so that a distance between the opposed surface and a conveying surface of the endless conveyor becomes smaller in the conveying direction, wherein crushing edges or crushing pins are provided on at least one of the conveying surface of the endless conveyor and the opposed surface of the opposed member, to direct toward the other, whereby the polymer mold products transported by the endless conveyor are pushed into a gap between the conveyor and the opposed member and crushed with the crushing edges or pins.
The crushing edge or pin is a member having a function for crushing the polymer mold product conveyed by the endless conveyor and pushed into a gap between the same and the opposed member. That is, even though shapes thereof are different from those generally thought from the feeling of words xe2x80x9cedge or pinxe2x80x9d, any member may be the crushing edge or pin according to the present invention, if it is provided on at least one of the conveying surface of the endless conveyor and the opposed surface of the opposed member to direct toward the other, and has the above-mentioned crushing function. The crushing edge or pin preferably has a sharp portion to be in contact with the polymer mold product because a larger crushing performance is exhibited thereby.
Preferably, the crushing edges or pins are provided on the conveying surface of the endless belt, and recesses or holes are provided on the opposed surface of the opposed member for allowing tip ends of the crushing edges or pins provided on the endless conveyor to pass through the same.
The opposed member may be a second endless conveyor.
To achieve the above-mentioned objects, one aspect of the identification system of the present invention is an identification device for irradiating a light beam to a polymer products conveyed by conveyor means, detect the reflected beam or the dispersed beam from the polymer product by a sensor element, and identify a kind of the polymer product based on the detected result, wherein the sensor element is disposed at a predetermined position in the vicinity of a conveying path of the polymer product, and a distance determination mechanism is disposed in the conveying means or in the vicinity thereof, for opposing the polymer product passing by the sensor element to the sensor element at a distance between the both.
Selectable polymers include, for example, rubber-like polymer, thermoplastic elastomer and resin. Of them, resin is more preferable. Additives in the resinous material and the selectable polymeric material are the same as described above.
The conveyor means may be an endless conveyor and the sensor element may be disposed at a predetermined position beneath the conveying path constituted by the endless conveyor, and the distance determination mechanism may be a light window provided at each of portions of the endless conveyor passing over the predetermined position.
According to this arrangement, the light beam is irradiated from beneath to the polymer conveyed on the endless conveyor through the light window, and the reflected or disperse light beam is received by the sensor element through the light window. The light window may be a mere slit but not be limited thereto. It may be formed of any light-permeable material unless it disturbs the detection of Raman disperse rays.
Alternatively, the conveyor means may be an endless conveyor and the sensor element may be disposed at a predetermined position on a side of the conveying path constituted by the endless conveyor, and the distance determination mechanism comprises a stopper member having a light window and disposed in front of the sensor element in the vicinity thereof and a guide for guiding the polymer product carried on the endless conveyor so that the polymer product is pushed against the light window of the stopper member to be able to pass by a front of the sensor element.
The stopper member has a function for limiting the displacement (deviating from the conveying direction) of the polymer pushed toward the stopper member by the guide while being conveyed on the endless conveyor at the position of the stopper member. The stopper member is provided with the light window, behind which is located the sensor element.
According to this arrangement, the polymer conveyed on the endless conveyor is guided by the guide to be brought into contact with the light window of the stopper member and irradiated with a light beam through the light window. The reflected or dispersed beam thereof is received by the sensor element through the light window. The light window may be a mere slit or be formed of any light-permeable material such as transparent glass plate not disturbing the detection of Raman disperse rays.
To achieve the above objects, one aspect of a method for cleaning thermoplastic resinous products comprises the steps of crushing the collected thermoplastic resinous products into crushed pieces, supplying the crushed pieces together with water into a cleaning device having a vessel and a rotary body disposed in a rotatable manner within the vessel, wherein at least part of the inner surface of the vessel and/or a surface of the rotary body to be in contact with the crushed resinous pieces is roughened, and rotating the rotary body to clean the crushed pieces.
According to this cleaning method, at least part of the inner surface of the vessel and/or a surface of the rotary body is roughened. The roughening may be carried out in any manners, provided the resin product could be sufficiently cleaned. Preferably, the surface irregularity has a depth in a range from 40 to 2000 xcexcm. When the roughened surface is brought into contact with the crushed resinous pieces, foreign matters such as coated film or label adhered on the surface of the crushed resinous piece are sufficiently scrubbed or scraped off and removed. If the depth of the irregularity is less than 40 xcexcm, the foreign matters are not sufficiently removable, while if exceeding 2000 xcexcm, the surface of the crushed resinous piece is excessively scraped off together with resin to lower the recovery percentage of resin. The depth of the irregularity is preferably in a range from 50 to 1000 xcexcm, more preferably from 60 to 500 xcexcm. If the depth is within this range, the foreign matters are sufficiently removed without excessively scraping resin off from the crushed piece.
The roughened surface in the interior of the vessel is preferably 1% or more, preferably 5% or more, more preferably 10% or more of a total area of the inner surface of the vessel and the surface of the rotary body to be in contact with the crushed resinous pieces. Degrees of the surface-roughening by the irregularity may be approximately equal or unequal both in the inner surface of the vessel and in the surface of the rotary body. The degree of the irregularity may be equal or unequal throughout the roughened inner surface of the vessel and/or the roughened surface of the rotary body.
According to this cleaning method, water is continuously supplied during the cleaning operation and acts as a lubricant between the surface of the crushed resinous piece and the roughened surface having the irregularity to prevent the surface of the crushed resinous piece from excessively being scraped off. Also, by the cooling action of water, the temperature rise in the crushed resinous piece can be prevented. Foreign matters such as coated film or label which have been once removed are quickly discharged out of the cleaning device not to adhere again to the crushed resinous pieces. Further, water is preferably continuously supplied and drained so that a water level in the cleaning device is maintained constant, while taking care to maintain a ratio in weight of the crushed pieces to the water constant, because the respective crushed resinous pieces continuously supplied can be evenly cleaned.
The cleaning is preferably carried out so that the ratio in weight of the crushed pieces to the water in the cleaning device is controlled to be 1:0.3 to 2 and water is continuously supplied and drained to maintain the interior temperature of the cleaning device at 70xc2x0 C. or lower. If the ratio of water is less than 0.3, the interior of the cleaning device is not sufficiently cooled, whereby the temperature rises above 70xc2x0 C. to soften and melt the crushed resinous pieces, which may disturb the cleaning operation. On the other hand, if the ratio of water exceeds 2, chances of contact of the crushed resinous pieces with the inner surface of the vessel and the surface of the rotary body, particularly those roughened to have the irregularity, becomes fewer. Even if the contact occurs, the crushed resinous piece does not be sufficiently pressed onto the surface, whereby the foreign matters such as coated film or label may not be completely and effectively removed.
Further, the rotary body has a screw blade for conveying the crushed resinous pieces and cleaning plates or pins for cleaning the crushed resinous pieces around a rotary shaft, and preferably rotates so that a linear speed of a tip end of the cleaning plate or pin is in a range from 0.5 to 20 m/sec. If the linear speed is 0.5 m/sec or less, the cleaning becomes insufficient, while if exceeding 20 m/sec, the interior temperature of the device rises, whereby it is difficult to maintain the temperature at 70xc2x0 C. or lower.
According to the above-mentioned method, it is possible to clean the crushed pieces of all thermoplastic resin products molded to have predetermined shapes by various molding methods such as compression molding, ejection molding or blow molding. These resin mold products may be molded either using a mold or using no mold but a mold die or others. Examples of the resin mold product include not only housings of home electric appliances such as TV sets or electric refrigerators or housings of OA equipment such as personal computers or printers but also parts of these apparatuses and/or broken ones thereof.
Although there is no limitation in kinds and shapes of the resin products, preferably, products of different kinds of resins are not mixed together. This is because, if different kinds of resins are mixed together, in general, characteristics inherent to the respective resin are largely deteriorated. Therefore, the resin products are preferably classified to the respective kinds and separately cleaned in advance. Also, the resin products may preferably be classified to have the same or similar color tones, such that products which color tones are largely different, for example, one being pale and light gray and the other being deep and dark gray, are not mixed together. If the products having largely different color tones are not mixed together, color tone of resin to be reused is easily adjustable.
Also, there is no limitation in size of the resin products, provided they can be crushed to pieces of a suitable size.
The resin products may be coated or plated. The coated film may be of any material usually used for coating resin. The plated layer may be of any metal usually used for plating resin.
The resin product is cleaned after being crushed into resinous pieces through a crushing operation in advance. The crushing operation may be carried out by a crusher usually used for crushing resin and capable of crushing the resin product into pieces of a size suitable for the cleaning, such as a hammer mill or a cutter mill. The crushing operation is preferably carried out under the forced cooling such as air cooling so that the resin product does not melt due to the heat generation.
The maximum length of the crushed resinous piece is preferably in a range from 1 to 30 mm, more preferably from 2 to 20 mm, most preferably from 3 to 10 mm. If the maximum length is less than 1 mm, micro-particles increases to dissipate the crushed resinous pieces in a pre-treatment process. On the other hand, if exceeding 30 mm, the cleaning becomes insufficient all over the surface of the crushed piece. There is no limitation in shape of the crushed resinous piece provided no problem occurs in the handling thereof. However, an excessively elongated one is unfavorable, and one having generally equal dimensions in all directions in a plan view is preferable, such as circular or square. Crushed resinous pieces of such a shape can be effectively cleaned even if an amount thereof is large. In this regard, if necessary, small crushed resinous pieces having the maximum length of approximately 1 mm or less, metallic powder or dust may be removed after crushing by a vibratory screen or others.
To achieve the above objects, in the cleaning system according to the present invention, a device is provided for cleaning thermoplastic resinous products comprising a vessel and a rotary body built-in in the vessel, wherein the vessel has an entrance port for the thermoplastic resinous products provided in an upper area of one end thereof, an exit port for the thermoplastic resinous products provided in a lower area of the other end thereof, a water supply port and a drainage port; the drainage port being connected to a drainage line for adjusting a water level; the rotary body having a rotary shaft, a screw blade provided on the circumference of the rotary shaft and at least one of a plurality of cleaning plates and cleaning pins; and at least part of the inner surface of the vessel and/or surfaces of at least one of the cleaning plates and the cleaning pins being roughened.
Also, to achieve the above objects, in the cleaning system according to the present invention, a device is provided as another aspect for cleaning thermoplastic resinous products comprising a vessel and agitating blades, wherein the vessel has an entrance port for crushed resinous pieces and a water supply port, both provided in an upper portion thereof, and an exit port for the crushed resinous pieces and a drainage port, both provided in a lower portion provided thereof; a drainage line for adjusting a water level being connected to the drainage port, and at least part of the inner surface of the vessel and/or surfaces of the agitating blades being roughened.
According to the above-mentioned cleaning device, at least part of surfaces to be in contact with the crushed resinous pieces is roughened to effectively scrub or scrape off a surface portion of the crushed resinous piece and sufficiently remove foreign matters such as coated film, plated layer applied to the surface, label or seal adhered to the surface or contaminants. At least part of the inner surface of the vessel and/or a surface of at least one of the screw blade, the cleaning plate and the cleaning pin may be roughened. Preferably, the inner surface of the vessel and a surface of at least one of the screw blade, the cleaning plate and the cleaning pin are roughened. Regarding the screw blade, the cleaning plate and the cleaning pin, a surface of at least one of the screw blade and/or the cleaning plate is more preferably roughened. Also, the inner surface of the vessel and at least part of a surface of the agitator blade is preferably roughened.
If necessary, the cleaning device may be combined with a water rinsing device, a dehydrator, a dryer, a vibratory screen, a wind type classifier and/or a metal sensor to assuredly remove foreign matters such as coated film, label or contaminants and obtain pure crushed resinous pieces. Such crushed resinous pieces may be used in any field requiring the same with no problems.